Fuel oil compositions containing formaldimine salts



FUEL OIL COMPOSRTKONS CONTAINING FORMALDEMENE SALTS Harry Andress, Jr., Pitman, N. 3., assignor to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Application May 10, 1955 Serial No. 507,479

6 Claims. (Cl. 44-63) this invention are petroleum-derived hydrocarbon fractions having initial boiling .points of at least about 300 F. and end points not higher than about 750 F., and

which boil substantially continuously throughout their distillation ranges. Such fuel oils are generally known as distillate fuel oils. It will be understood, however, that this term is not restricted to straight-run distillate fractions. Thus, the distillate fuel oils can also be catalytically or thermally cracked distillates or they may be mixtures of straight-run distillates, naphthas, and the like, with cracked distillate stocks. Moreover, such fuel oils can be treated in accordance with well known commercial methods, such as, acid or caustic treatment, solvent refining, clay treatment, etc.

The distillate fuel oils are characterized by their relatively low viscosities, pour points and the like. The principal property which characterizes the contemplated fuel oils, however, is the distillation range. As mentioned hereinbefore, this range will lie between about 300 F. and about 750 F. Obviously, the distillation range of each individual fuel oil will cover a narrower range falling, nevertheless, within the above-specified limits. Likewise, each fuel oil will boil substantially continuously throughout its distillation range.

The fuel oils particularly contemplated herein are the Nos. 1, 2 and 3 fuel oils used in domestic heating and as Diesel fuel oils, particularly those made up chiefly or entirely of cracked distillate stocks. The domestic heating oils generally conform to the specifications set forth in ASTM Specifications D396-48T. The specifications for Diesel fuels are defined in ASTM Specifications D975-48T.

As is well known,fuel oils, particularly the No. 2 fuel oils, are prone to develop undesirable color and form sediment during prolonged storage periods. Although the quality of the fuel oil is not believed to be affected to any significant degree by color development, color is generally considered to be an indication of degradation of the fuel and customers are generally resistant to highily colored fuel oils. 'Sediment formation in fuel oils,

of course, is a serious problem since this'sediment adheres to surfaces with which it comes in contact, such as the screens, filters and nozzles of burners using the oil, eventually causing the clogging of equipment parts. As a consequence, frequent cleaning and even replacement of parts is required. Many additives have been proposed heretofore as sediment inhibitors. However, these additives have failed to improve the color of the fuel oil and in some cases actually degrade the color. Accordingly,'resort has been made to other additives, in addition to the sedimentation inhibitors, for the purpose of improving color stability.

It'has now been found that improved color stability as well as inhibition of sedimentation can be achieved by the addition'of a single additive to the fuel oil. Thus,

. 2,867,515 Patented Jan. 6, 1959 it has now been found that when relatively small amounts of certainformaldimine salts are added to the fuel oil, the formation of color and sedimentation therein is ef fectively inhibited. Accordingly, it is an object 'of this invention to provide fuel oils having improved xcolor stability and "resistance to sedimentation. Another object is to provide a method for inhibiting the formation of color and sediment in fuel oils during storage. A further specific object is to provide distillate fuel oils containing minor amounts of certain formaldimine salts. Other objects and advantages of the invention will be come apparent from the following detailed description.

As afore-indicated the addition agents contemplated herein are the substantially neutral formaldimine-salts produced by the reaction of certain organic acids with certain formaldimines.

The following classes of acidic compounds form formaldimine salts suitable for use in the invention.

(a) Carboxylic acids of the aliphatic, aromatic or naphthenic type. As non-limiting examples of such acids, there may be mentioned: aliphatic acids, such as formic, acetic, propionic, caprylic, decanoic, lauric, stearic, oleic, linoleic and abietic acids; aromatic acids, such as benzoic, salicylic or phthalic acids, which may or may not have aliphatic substituents, suchas diamyl benzoic acid, wax benzoic acid and the like. Of the carboxylic acids, the'naphthenic acids are particularly preferred.

(b) Phenols, including phenol, naphthols, catechols, ,etc.,' which may or may not carry an aliphatic substituent. As non-limiting examples of such acids, there may be mentioned phenol, diamylphenol, wax phenol, cresol, catechol, dinonylcatechol, hydroquinone, pyrogallol and wax pyrogallol.

(c) Thiophenols, such as thiophenol, thiocresol,thi onaphthol, thioxylenol and the like.

(d) Thiols, such as ethyl, propyl, octyl, dodecyl, tetradecyl, hexadecyl, octadecyl and octadecenyl thiols.

(e) Mixtures of acids may also be used in the invention. One commercial mixture, for example, is Unitol S (Example 1, below) which is a refined tall-oil comprised essentially of rosin acids and high molecular weight fatty acids.

The formaldimines suitable for reaction with the aforedescribed acids to provide formaldimine salts utilizable in the invention are: (1) those produced by the condensation of formaldehyde with a normal aliphatic primary amine having from about '8 to about 18 carbon atoms, and (2) those obtained by the condensation of formaldehyde with an aliphatic, tertiary 'alkyltype'primary amine having from 4 to about 24 carbon atoms per molecule. These latter amines are characterized by the structure:

i. e., the nitrogen atom of the amine group is attached directly to a tertiary carbon atom of the alkyl group. In general, the reaction involved with either type of amine produces a compound of the formula RN=CH where R is an aliphatic radical corresponding to the aliphatic radical of the amine reactant. The normal aliphaticprimary amines, however, do not form stable formaldimine monomers, but trimerize under the conditions of the condensation reaction to form compounds of the formula (RN=CH such compounds having the structure:

H C H: R

and tertiary octyl amine,

On the other hand, theprirnary alkyl amines having a .tertiarycarbon atom attached to the nitrogen atom do not undergo the trimerization reaction, but form stable, distillable monomeric formaldimines of the general formula .RN=CH where R represents an aliphatic hydrocarbon ,radical corresponding to the aliphatic radical of the -.tertiary alkyl amine.

:1. The formaldimines are prepared by the reaction of the Hairline" and the formaldehyde in a 1:1 molar ratio, using anyiiof" the .methods well known to the art. Ordinarily, ..:the. reaction is exothermic. ..-action"to.comp1eti0n the water formed during thereaction zr'nus't be removed. r.This can be, accomplished by:heating .'.the'. reaction mixture to a temperatureabove the boiling -pbiiit'ofwater or by utilizing a. suitable. 'nonpolar solvent,

'However,:to bring the re such as benzenetor' toluene,.in the reaction and removing .sthe'water by azeotropic'distillation. The. invention, how- 1 ever; is'. not limited to any particular method for producing :Jithe various formaldimine reactants.

The normal aliphatic primaryamines 'which produce .the :trimeric formaldimines contemplated herein may be either saturated or unsaturated. Suitable amines are,

I for example, n-octyl amine, n-octenyl amine, n-decyl amine, n-undecyl amine, n-dodecenyl amine, n-tetradecyl' amine, n-pentadecyl amine, n-hexadecyl amine, n-octadecyl amine, n-octadecenyl amine and n-octadecadienyl amine. V i

- ;-Mixtures of primary normal aliphatic amines, such as .-those manufactured by Armour & Company of Chicago, zlllinois, under the Armeen trade name, are also highly suitable for use herein. The following Armeens are particularly contemplated: Armeen C, Armeen S, Arrnee'n'T, Armeen 8, Armeen 10, Armeen 'meen l4,- Armeen 16 and Armeen 18. 1

-Armeen C is derived from coconut oil, Armeen T from tallow,.'and ArmeenS from soy bean oil. These amines are mixtures of primary aliphatic normal amines 'having the weight percentage compositions shown in Table I.

TABLE I Normal Amine Armeen Armeen Armeen T" S" C" .Octyl 8 Decyl. 9 Dodecyl. 47 Tetradecyl. 18 HexadecyL- 8 'Octadccyl 26 10 Octadecenyl 45 35 5 Octadecadienyl 45 The other Armeens are mixtures of primary normal aliphatic amines containing predominantly the number of carbon atoms specified in the code number.

Of the tertiary alkyl type primary amines, tertiary butyl amine,

CHs-C-NH2 are particularly contemplated. However, commercial 'mlxtures of tertlary alkyl type primary amines, such as those manufactured and sold under the trade name Primenes are also highly suitable in the invention. Pri- The formaldimine salts of the invention are prepared by reaction ofthe formaldimine with the organic acid at moderately elevated temperatures, i. e., from about 50 C. to about 175 C., preferably from about 75 C. to about 125 C. The reactionis exothermic and is generally vigorous. In conducting the reaction, therefore, the temperature should be controlled by cooling and heating as required. The reaction is usually completed in, from about 1 to about hours. The following equationrepresents a typical reaction between a monocarboxylic acid and a formaldimine to form a formaldimine salt: a

RCOOH-l-R'N=CH RCOOH.RN=CH T etc. and R represents a tertiary alkyl radical having from "about 4 to about 24 carbon atoms and which is linked l'itogthefnitrogen atom through a tertiary carbon atom thereof.

- In the case of the formaldimine trimers, i. e., formaldimines derived from normal primary aliphatic amines,

the reaction involves /a mole of the formaldimine per equivalent weight of the acid. By equivalent weight, as used herein, is meant that weight in grams of the organic acid which will supply one atomic weight (1.008 grams) of acid-hydrogen to the reaction. The following empirical equation represents a typical reaction between a monocarboxylic acid and a formaldimine trimer to form a formaldi-mine salt of the character herein contemplated,

where R represents hydrogen or an aliphatic radical, such as alkyl, aryl, alkenyl, alkaryl, aralkyl, cycloalkyl, etc., and .R represents a normal, aliphatic radical having from about 8 to about 18 carbon atoms.

A mixture of 380 grams (1.14 M) of fUnitol S (a commercial, refined tall oil comprised essentially of rosin acids and high molecular weight fatty acids) and 96.5

grams (1.14 M) of the formaldimine of tertiary butyl primary amine was stirred at about 75 C. for four hours to form the Unitol S salt of tertiary butyl formaldimine.

Example 2 A mixture of 6 2 grams (0.22 M) of oleic acid and 52 grams (0.22 M) of the formaldimine of Primene 81 was stirred at 145 C. for two hours to form the oleic acid salt of the formaldimine of Primene 81.

Example 3 A mixture of grams (0.85 M) of an acid oil obtained by the causticextraction of cracked gasoline and comprised essentially of a mixture of phenols and aromatic and aliphatic mercaptans was stirred with 259 grams (0.85 M) of the formaldimine of Primene JM for one hour at C. The product produced was a mixture of phenolic, thiophenolic and thiolie salts of the formaldimine of Primene JM.

Example 4 STORAGE TESTS The ability of the formaldimine salts of the invention as color stabilizers and sediment inhibitors in stored fuel oils is illustrated in the data presented in Table II, which vshows the results of a series of storage tests conducted -1DI1 a base fuel and blends of the base fuel with the form- .alrl nesal f h e o n e m The b s fuel oil used in all of the tests was comprised of 60% catalytically cracked component and 40% Straight run component and had a boiling range of approximately 320 F. to 640 F.

The tests used to determine the sedimentation characteristics ofthe fuel oils were the 110 F.--storage test and the 80F. storage test. In the 110 F. storage test, a SOD-milliliter sample of the fuel oil;under test is .placed in a convecte'd oven maintained at 110 for aperiod of weeks. 'Ihnfthes'ampleis rem'ove'd from the oven "and cooled. Thec'o'oled's'ample is filtered through a tared asbestos filter (Gooch crucible) 'toire'm'ove the insoluble "matter. The weight 'ofsuchhiatten -in inilligrams, is reported as the "amount "or sediment. 'Ihe 80 F. Storage "test is' conducted 'in'a similar manner, with the exception that atempe'ratufe 'of'80' F. is 'used and the test is run for a period of 'thfee'fnonths. "In'bo'th'tests, a sample of the uninhibited base oil is run along with the fuel oil blend under test. The eifectiveness of a fuel oil composition containing an inhibitor is determined by comparing the test data therefor with the test data for the uninhibited base oil.

The color characteristics of the fuel oil are determined by measuring the percentage of light transmission by the oil after it is subjected to the storage tests. The light transmission is measured by means of a Lumetron Colormeter.

As shown in Table 11, each of the formaldimine salts tested effected a substantial reduction in color and sediment formation in the oil during storage.

TABLE II Fuel oil storage tests i What is claimed is:

1. A distillate fuel oil containing a small amount, sufiicient to inhibit the colorformation and sedimentation insaid oil, of a formaldimine salt formed by reacting (A) a formaldimine selected from thegroup consisting of (1) a formaldimine of the general formula v(RN=CH where R is a normal primary aliphatic hydrocarbon radical containing 'from about 8 to about 18 carbon-atoms and (2') a formaldimine of the general formula RN=CH whereR is "a tertiary alkyl-radical containing from about 4 to about '24 carbon atoms and which is linked to the nitrogen atom'thr'ough a ter'tiary carbon atom thereofi'with (B) an acidic organic compound s'electe'dfromlthe group consisting of carboxylic acids, phenols, thiophenols and thiols, thecarboxyl, hydroxyl and thiol radicals in said compound being in all instances attached "to "an'otherwis'e unsubstituted hydrocarbon radical, at a temperature of from about C. to about 175 C., the proportions of formaldimine used in the reaction being about /3 mole per equivalent weight of the acidic organic compound when the formaldimine corresponds to the formula (RN=CH and about 1 mole per equivalent weight of the acidic organic compound where the formaldimine corresponds to the formula RN=CH 2. A distillate fuel oil containing a small amount, sufficient to inhibit the color formation and sedimentation in said oil, of a formaldimine salt formed by reacting about 1 mole proportion of a formaldimine of the general formula RN=CH Where R is a tertiary alkyl 6 Weeks Storage 3 Months Storage 110 F. 80 F. Cone, Inhibitor Added 1b./l,000

Bbls. Color, Per- Sediment, Color, Per- Sediment,

cent Trauslug/liter cent TransmgJliter mission mission None 0 36. 2 64. 0 42. 0 67. 0 Uni 01 S Salt of tbutyl Formaldimine (Exene 81" Formaldlmine (Example 2) 100 45. 0 11. 0 58. 4 8. 0 Mixed (phenolic-thiophenolic-thiolic) Salts of Primene J M Formaldimine (Example 3)-..- 100 46. 0 8. 0 53.4 8.0 Naphthenic Acid Salt of Primene 81" Formaldimine (Example 4) 100 61.0 4. 2 76. 3 4. 2

In order to effect significant improvement in the fuel oil with respect to sedimentation and color inhibition, at least about 5 pounds per 1000 barrels of the formaldimine salt should be added to the oil. In certain instances, however, the use of up to about 200 pounds per 1000 barrels may be found desirable. The usual amount, however, will be from about 50 to about 100 pounds per 1000 barrels. Expressed in terms of weight percent, the amount used will range, broadly, from about 0.001% to about 0.05%. It is also contemplated to prepare the additives of the invention in the form of concentrated solutions containing specified quantities thereof. Such solutions, suitable for marketing, can be conveniently added to fuel oils in amounts to provide the desired improvements therein.

If desired, the fuel oil compositions contemplated herein as well as the additive concentrates may also contain other addition agents designed to impart other improved characteristics to said fuel oil compositions. Thus, for example, there can be present foam inhibitors, anti-rust agents, burning and ignition quality improvers, etc.

Although the invention has been described and illustrated herein by means of certain specific embodiments, it is not intended that the scope of the invention be limited in any way thereby, but only as indicated in the following claims.

radical having from 4 to about 24 carbon atoms and which is linked to the nitrogen atom through a tertiary carbon atom thereof, with about 1 equivalent weight of a carboxylic acid, the carboxyl radical thereof being in all instances attached to an otherwise unsubstituted hydrocarbon radical, at a temperature of from about 50 C. to about C.

3. A distillate fuel oil containing a small amount, suflicient to inhibit the color formation and sedimentation in said oil, of a formaldimine salt formed by reacting about 1 mole proportion of a mixture of formaldimines of the general formula RN=CH where R is a tertiary alkyl radical containing from about 12 to about 15 carbon atoms and which is linked to the nitrogen atom through a tertiary carbon atom thereof, with about 1 equivalent weight of oleic acid, at a temperature of from about 50 C. to about 175 C.

4. A distillate fuel oil containing a small amount, sufli cient to inhibit the color formation and sedimentation in said oil, of a formaldimine salt formed by reacting about 1 mole proportion of a mixture of formaldimines of the general formula RN=CH where R is a tertiary alkyl radical containing from about 12 to about 15 carbon atoms and which is linked to the nitrogen atom through a tertiary carbon atom thereof, with about 1 equivalent 7 weight of naphthenic acid, at a temperature of from about SOf, C. to about. 175 C. a

5. A distillate fuel oil containing asmall amount, sufficient to inhibit the color formation and sedimentation in said oil, of a formaldimine'salt formed by reacting about 1 mole proportion of a mixture offormaldimines of the general formula RN=CH where R is a tertiaryalkyl radical containing from about 18 vto about 24 carbon atoms and which is linked to the nitrogen .atomthrough atertiary .carbon atomthereof, with about 1 equivalent weight'of an-acid'oil consistingessentiallyof a mixture of. phenols, thiophenols and thiols, the hydroxyl and thiol radicals of which are in all instances attached to an otherwise unsubstituted hydrocarbon radical,.a t a temperature of from about 50 C. to about 175 C.

6; A distillate fueloil containing a small amount,

"sufficient to inhibit the color formation and sedimentation in said oil, of a formaldimine salt .formed by reacting about 1 mole: firoportion of the formaldimine of tertiary jbutyl .primar'yiamine with about 1 equivalent weight of tall oil, at a temperature of from about 50. C. to about 175 C.

References Cited in the file of this patent -UNITED STATES PATENTS 2,701,187 Andress et'al. Feb. 1, 1955 

1. A DISTILLATE FUEL OIL CONTAINING A SMALL AMOUNT, SUFFICIENT TO INHIBIT THE COLOR FORMATION AND SEDIMENTATION IN SAID OIL, OF A FORMALDIMINE SALT FORMED BY REACTING (A) A FORMALDIMINE SELECTED FROM THE GROUP CONSISTING OF (1) A FORMALDIMINE OF THE GENERAL FORMULA (RN=CH2)3, WHERE R IS A NORMAL PRIMARY ALIPHATIC HYDROCARBON RADICAL CONTAINING FROM ABOUT 8 TO ABOUT 18 CARBON ATOMS AND (2) A FORMALDIMINE OF THE GENERAL FORMULA FORMULA RN=CH2, WHERE R IS A TERTIARY ALKYL RADICAL CONTAINING FROM ABOUT 4 TO ABOUT 24 CARBON ATOMS AND WHICH IS LINKED TO THE NITROGEN ATOM THROUGH A TERTIARY CARBON ATOM THEREOF, WITH (B) AN ACIDIC ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF CARBOXYLIC ACIDS, PHENOLS, THIOPHENOLS AND THIOLS, THE CARBOXYL, HYDROXYL AND THIOL RADICALS IN SAID COMPOUND BEING IN ALL INSTANCES ATTACHED TO AN OTHERWISE UNSUBSTITUTED HYDROCARBON RADICAL, AT A TEMPERATURE OF FROM ABOUT 50*C. TO ABOUT 175*C., THE PROPORTIONS OF FORMALDIMINE USED IN THE REACTION BEING ABOUT 1/3 MOLE PER EQUIVALENT WEIGHT OF THE ACIDIC ORGANIC COMPOUND WHEN THE FORMALDIMINE CORRESPONDS TO THE FORMULA (RN=CH3)3 AND ABOUT 1 MOLE PER EQUIVALENT WEIGHT OF THE ACIDIC ORGANIC COMPOUND WHERE THE FORMALDIMINE CORRESPONDS TO THE FORMULA RN=CH2. 